Here is the procedures of making four-layer PCB for your reference:

Section Header

Processing data = >Board cutting = > Inner layer trace = > Outer layer trace= > Drilling = > Electroplating = >Solder mask = >Silk-screen= > Surface treatment = > Appearance = > Testing = > Packaging

1.jpg
        http://www.58pcba.com/index.php?id=566
    
Shenzhen Grande
Specialized in One-Stop PCBA Service. http://www.58pcba.com/